1. Field of the Invention
The invention relates to a process for the preparation of pure aqueous solutions of betaines of the formula 1 ##STR1## in which R.sup.1 is an alkyl radical having 6 to 22 carbon atoms, preferably 8 to 18 carbon atoms, or a radical of the formula R'CONH(CH.sub.2).sub.z --, in which R' is an alkyl radical having 5 to 21 carbon atoms, preferably having 5 to 17 carbon atoms, and z is 2, 3 or 4,
R.sup.2 is an alkyl radical having 1 to 4 carbon atoms or a radical of the formula --(CH.sub.2).sub.m --OH, in which m is 1, 2 or 3, PA1 R.sup.3 is an alkyl radical having 1 to 4 carbon atoms or a radical of the formula --(CH.sub.2).sub.m --OH mentioned and PA1 y is 1, 2 or 3, by reaction of a tertiary amine of the formula 2 EQU R.sup.1 --NR.sup.2 R.sup.3 ( 2) PA1 R.sup.2 is an alkyl radical having 1 to 4 carbon atoms or a radical of the formula --(CH.sub.2).sub.m --OH, in which m is 1, 2 or 3, PA1 R.sup.3 is an alkyl radical having 1 to 4 carbon atoms or a radical of the formula --(CH.sub.2).sub.m --OH mentioned and PA1 y is 1, 2or 3, by reaction of a tertiary amine of the formula 2 EQU R.sup.1 --NR.sup.2 R.sup.3 ( 2) PA1 R.sup.2 is an alkyl radical having 1 to 4 carbon atoms or a radical of the formula --(CH.sub.2).sub.m OH, in which m is 1, 2 or 3, PA1 R.sup.3 is an alkyl radical having 1 to 4 carbon atoms or a radical of the formula --(CH.sub.2).sub.m OH mentioned and PA1 y is 1, 2or 3, by reaction of a tertiary amine of the formula 2 EQU R.sup.1 --NR.sup.2 R.sup.3 ( 2)
in which R.sup.1, R.sup.2 and R.sup.3 have the meanings given, with an .omega.-halocarboxylic acid of the formula 3 EQU X--(CH.sub.2).sub.y --COOH (3)
in which X is a halogen, preferably Cl, and y has the meaning given, and with an alkali metal hydroxide in the aqueous phase.